Atherosclerotic vascular disease is the leading cause of death in the country. Current therapeutic modalities, although effective, are not ideal and are associated with significant morbidity, mortality and expense. The aim of this project is to develop and apply the techniques of angioscopy and laser angioplasty for treatment of atherosclerotic disease. Specific goals are a) to develop a fiberoptic waveguide that permits simultaneous visualization and lasing, b) to evaluate the efficacy of perfluorocarbon solutions and coronary sinus retroperfusion for provision of myocardial oxygenation during temporary cessation of coronary artery blood flow, c) to define the dose-response of a variety of lasers on vascular tissue, d) to examine the physical and chemical changes that occur when vascular tissue is irradiated by laser energy, e) to determine if plaque disruption can be accomplished by photochemical rather than thermal laser action, f) to determine the informational value of direct intravascular visualization of atherosclerotic disease, g) to determine the efficacy and safety of angioscopy and laser angioplasty in man.